The present invention relates to a bicycle rear derailleur shifting controller, and more particularly to a simple structure of bicycle rear derailleur shifting controller, which is inexpensive to manufacture, and which can easily be controlled to shift the rear derailleur mechanism of the bicycle.
A regular bicycle rear derailleur-shifting controller is generally comprised of a base and a rotary knob. The base comprises a coupling tube coupled to the handlebar of the bicycle. The rotary knob is fastened to an endpiece at one end of the derailleur cable, and rotatably coupled to the coupling tube of the base. Further, an arcuate spring member and a detent section are respectively provided at the base and the rotary knob. The arcuate spring member comprises an indexing projection shifted between notches at the detent section. The derailleur cable is driven to shift the rear derailleur mechanism of the bicycle upon rotary motion of the rotary knob. This structure of bicycle rear derailleur shifting controller is not satisfactory in function. Because the derailleur cable is wound round the coupling tube of the base and turned radially with the rotary knob around the coupling tube, it tends to be hindered by internal structure of the base, causing the rear derailleur mechanism shifting operated unable to be accurately achieved.
The present invention has been accomplished to provide a bicycle rear derailleur-shifting controller, which eliminates the aforesaid problem. According to one aspect of the present invention, the bicycle rear derailleur shifting controller comprises a base having a shell and a coupling tube extended from the shell, a rotary knob having a body coupled to the coupling tube of the base and a handgrip formed integral with one end of the body, the body having a recessed portion, a raised block, and a locating hole through the raised block, a spring plate fixedly mounted inside the shell of the base, the spring plate having a protruding portion, an arched positioning block mounted in the recessed portion at the body of the rotary knob, the positioning block having a series of notches meshed with the protruding portion of the spring plate to guide rotary motion of the rotary knob on the coupling tube and to hold the rotary knob in position after a rotary motion, a cover plate covered on the recessed chamber to stop the rotary knob from axial movement on the coupling tube of the base, and a derailleur cable moved with the rotary knob to shift the rear derailleur mechanism of the bicycle. According to another aspect of the present invention, the cover plate comprises a plurality of projections raised from a smoothly curved side edge thereof and inserted into the recessed portion at the body of the rotary knob to stop the rotary knob from axial movement along the coupling tube.